This thesis evaluates the effects of seed characteristics and environmental factors
during and after maturation on hardseededness of wild beans (Phaseolus vulgaris L.).
Accessions of wild beans from Durango and Tlaxcala in Mexico and 38 recombinant
inbred lines from crossing wild and common beans were studied. Factors researched
included temperature and water stress during seed maturation, drying temperature on
and off the mother plant, seed size, testa colour and thickness of hilum and lens.
The research traced the behaviour of individual wild bean seeds back to the seed
positions in the pods in which they developed. Flowers of glasshouse-grown plants at
Reading University were tagged individually and seed positions in the pods were
recorded at every stage.
Seeds of the accession Durango took longer to lose hardseededness (Le. were more
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hard seeded) at a maturation temperature of 25Ã‚Â°C and when exposed to terminal water
stress. In contrast, the tirhe to lose hardseededness diminished with a lower maturation
temperature (l9Ã‚Â°C) and terminal water stress. This can be explained by the higher
seed moisture content of seeds grown at 19Ã‚Â°C.
If the seed closest to the point of attachment of the pod to the mother plant was hard,
other seeds in the pod were also likely to be hard. Hardseededness increased with
increase in number of seeds in each pod. Small seeds were also more likely to be hard
seeded. Allowing seeds to dry naturally on the mother plant produced more hard seeds
than harvesting early and drying the seeds off plant, even though the seeds dried off
plant were at a lower moisture content. There was no evidence that the mechanism of
hardseededness related to the thicknesses of hilum and lens. Results are discussed to
show how hardseededness of wild beans could be used to maintain seed quality during
storage.